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Accepted
billinkc
Asked: 2011-09-02 08:12:00 +0800 CST

将 varchar 数据转换为日期时间失败

  • 772

我们正在将数据从遗留表（所有 varchar 字段）移动到强类型对应提示欢呼

作为这项工作的一部分，如果所有数据都可以正确转换为适当的类型，我们将从基本 Entity 表中获取数据并将其转储到 Entity_New 中。否则，它将进入名为 Entity_Bad 的现有表的副本。

我们有一个规则引擎来验证数据和类型，理论上，即使数据存储在字符字段中，数据也应该是干净的。现实是我在这里发帖，因为有些东西已经关闭，我找不到它。Entity 中的 CompletionDate 字段为 varchar(46) NULL

环境是

productversion  productlevel   edition
10.0.4064.0     SP2            Enterprise Edition (64-bit)

我的脚本展示了我在做什么以及什么是但不工作

SET NOCOUNT ON

DECLARE
    @startid int = 0
,   @stopid int = 796833


-------------------------------------------------------------------------------
-- Check doesn't find anything wrong with CompletionDate
-------------------------------------------------------------------------------
SELECT
    1
FROM
    [dbo].[Entity] E
    INNER JOIN
        dbo.EntityBatch_New PB
        ON E.FiscalYear = PB.FiscalYear
            AND E.HashCode = PB.HashCode
            AND E.AAKey = PB.AAKey
            AND PB.ProcessResultCode IN ('A','W','M')
WHERE
    PB.EntityBatchId BETWEEN @StartId AND @StopId
    AND
    (
        -- check
        (isDate(E.[CompletionDate]) = 0 AND E.[CompletionDate] IS NOT NULL)
        AND (isDate(E.[CompletionDate]) = 1 AND CAST(E.[CompletionDate] AS datetime) BETWEEN '1753-01-01T00:00:00.000' AND '9999-12-31T23:59:59.997')
    )

-------------------------------------------------------------------------------
-- Only row that shows as non-date is the NULL one, which is expected
-------------------------------------------------------------------------------
SELECT DISTINCT
    (E.[CompletionDate] )
,  isDate(E.[CompletionDate])
FROM
    [dbo].[Entity] E
    INNER JOIN
        dbo.EntityBatch_New PB
        ON E.FiscalYear = PB.FiscalYear
            AND E.HashCode = PB.HashCode
            AND PB.ProcessResultCode IN ('A','W','M')
    -- Ensure we aren't pulling something we have already processed
    LEFT OUTER JOIN
        [dbo].[Entity_new] N
        ON N.HashCode = E.HashCode
            AND N.FiscalYear = E.FiscalYear
                AND E.AAKey = N.AAKey
    -- Ensure we aren't pulling something we have already processed (or was bad)
    LEFT OUTER JOIN
        [dbo].[Entity_bad] BAD
        ON BAD.HashCode = E.HashCode
            AND BAD.FiscalYear = E.FiscalYear
                AND E.AAKey = BAD.AAKey
WHERE
    PB.EntityBatchId BETWEEN @StartId AND @StopId
    AND N.FiscalYear IS NULL
    AND BAD.FiscalYear IS NULL
ORDER BY 2

-------------------------------------------------------------------------------
-- Make the cast and it blows with
-- The conversion of a varchar data type to a datetime data type resulted in an out-of-range value.
-------------------------------------------------------------------------------
SELECT DISTINCT
    (E.[CompletionDate] )
,   CAST(E.[CompletionDate] AS datetime) AS [CompletionDate]
FROM
    [dbo].[Entity] E
    INNER JOIN
        dbo.EntityBatch_New PB
        ON E.FiscalYear = PB.FiscalYear
            AND E.HashCode = PB.HashCode
            AND PB.ProcessResultCode IN ('A','W','M')
    -- Ensure we aren't pulling something we have already processed
    LEFT OUTER JOIN
        [dbo].[Entity_new] N
        ON N.HashCode = E.HashCode
            AND N.FiscalYear = E.FiscalYear
                AND E.AAKey = N.AAKey
    -- Ensure we aren't pulling something we have already processed (or was bad)
    LEFT OUTER JOIN
        [dbo].[Entity_bad] BAD
        ON BAD.HashCode = E.HashCode
            AND BAD.FiscalYear = E.FiscalYear
                AND E.AAKey = BAD.AAKey
WHERE
    PB.EntityBatchId BETWEEN @StartId AND @StopId
    AND N.FiscalYear IS NULL
    AND BAD.FiscalYear IS NULL


-------------------------------------------------------------------------------
-- Dump the values into a temporary table to slice and dice the values
-------------------------------------------------------------------------------
DECLARE @debug TABLE
(
    CompletionDate varchar(46) NULL
)
INSERT INTO
    @debug
SELECT DISTINCT
    (E.[CompletionDate] )
FROM
    [dbo].[Entity] E
    INNER JOIN
        dbo.EntityBatch_New PB
        ON E.FiscalYear = PB.FiscalYear
            AND E.HashCode = PB.HashCode
            AND PB.ProcessResultCode IN ('A','W','M')
    -- Ensure we aren't pulling something we have already processed
    LEFT OUTER JOIN
        [dbo].[Entity_new] N
        ON N.HashCode = E.HashCode
            AND N.FiscalYear = E.FiscalYear
                AND E.AAKey = N.AAKey
    -- Ensure we aren't pulling something we have already processed (or was bad)
    LEFT OUTER JOIN
        [dbo].[Entity_bad] BAD
        ON BAD.HashCode = E.HashCode
            AND BAD.FiscalYear = E.FiscalYear
                AND E.AAKey = BAD.AAKey
WHERE
    PB.EntityBatchId BETWEEN @StartId AND @StopId
    AND N.FiscalYear IS NULL
    AND BAD.FiscalYear IS NULL


-------------------------------------------------------------------------------
-- This is operating on all the same values as the failing query but magically works
-------------------------------------------------------------------------------
SELECT ALL
    CAST(E.[CompletionDate] AS datetime) AS [CompletionDate]
FROM
    @debug E



-------------------------------------------------------------------------------
-- Clearly, something is amiss when we extract the data so process each row
-- and find the culprit that way. Except this finds nothing wrong
-------------------------------------------------------------------------------
DECLARE @hash uniqueidentifier
,   @zee_date varchar(46)
,   @real_date datetime

DECLARE
    CSR CURSOR READ_ONLY
FOR
SELECT
    E.HashCode
,   E.[CompletionDate]
FROM
    [dbo].[Entity] E
    INNER JOIN
        dbo.EntityBatch_New PB
        ON E.FiscalYear = PB.FiscalYear
            AND E.HashCode = PB.HashCode
            AND PB.ProcessResultCode IN ('A','W','M')
    -- Ensure we aren't pulling something we have already processed
    LEFT OUTER JOIN
        [dbo].[Entity_new] N
        ON N.HashCode = E.HashCode
            AND N.FiscalYear = E.FiscalYear
                AND E.AAKey = N.AAKey
    -- Ensure we aren't pulling something we have already processed (or was bad)
    LEFT OUTER JOIN
        [dbo].[Entity_bad] BAD
        ON BAD.HashCode = E.HashCode
            AND BAD.FiscalYear = E.FiscalYear
                AND E.AAKey = BAD.AAKey
WHERE
    PB.EntityBatchId BETWEEN @StartId AND @StopId
    AND N.FiscalYear IS NULL
    AND BAD.FiscalYear IS NULL


OPEN CSR

FETCH NEXT FROM CSR INTO
    @hash, @zee_date

WHILE (@@fetch_status = 0)
BEGIN
    BEGIN TRY
        SELECT @real_date = cast(@zee_date AS datetime)
    END TRY
    BEGIN CATCH
        print 'In here'
        print @hash
        print @zee_date
        SELECT @hash, @zee_date
    END CATCH


    FETCH NEXT FROM CSR INTO
        @hash, @zee_date

END

CLOSE csr
DEALLOCATE csr

在用上面的代码墙批评你之后，这里是上面查询操作的 406 个唯一值。

DECLARE @REAL_DATES TABLE
(
    CompletionDate varchar(46) NULL
)

INSERT INTO
    @REAL_DATES 
SELECT
    NULL
UNION ALL SELECT '19000101'
UNION ALL SELECT '20100208'
UNION ALL SELECT '20100228'
UNION ALL SELECT '20100309'
UNION ALL SELECT '20100314'
UNION ALL SELECT '20100401'
UNION ALL SELECT '20100409'
UNION ALL SELECT '20100420'
UNION ALL SELECT '20100427'
UNION ALL SELECT '20100429'
UNION ALL SELECT '20100507'
UNION ALL SELECT '20100615'
UNION ALL SELECT '20100617'
UNION ALL SELECT '20100629'
UNION ALL SELECT '20100701'
UNION ALL SELECT '20100703'
UNION ALL SELECT '20100704'
UNION ALL SELECT '20100706'
UNION ALL SELECT '20100709'
UNION ALL SELECT '20100713'
UNION ALL SELECT '20100714'
UNION ALL SELECT '20100715'
UNION ALL SELECT '20100716'
UNION ALL SELECT '20100720'
UNION ALL SELECT '20100721'
UNION ALL SELECT '20100726'
UNION ALL SELECT '20100727'
UNION ALL SELECT '20100728'
UNION ALL SELECT '20100729'
UNION ALL SELECT '20100731'
UNION ALL SELECT '20100801'
UNION ALL SELECT '20100802'
UNION ALL SELECT '20100803'
UNION ALL SELECT '20100804'
UNION ALL SELECT '20100807'
UNION ALL SELECT '20100809'
UNION ALL SELECT '20100810'
UNION ALL SELECT '20100811'
UNION ALL SELECT '20100813'
UNION ALL SELECT '20100817'
UNION ALL SELECT '20100819'
UNION ALL SELECT '20100820'
UNION ALL SELECT '20100822'
UNION ALL SELECT '20100823'
UNION ALL SELECT '20100825'
UNION ALL SELECT '20100827'
UNION ALL SELECT '20100828'
UNION ALL SELECT '20100830'
UNION ALL SELECT '20100831'
UNION ALL SELECT '20100901'
UNION ALL SELECT '20100902'
UNION ALL SELECT '20100904'
UNION ALL SELECT '20100907'
UNION ALL SELECT '20100908'
UNION ALL SELECT '20100909'
UNION ALL SELECT '20100910'
UNION ALL SELECT '20100911'
UNION ALL SELECT '20100913'
UNION ALL SELECT '20100916'
UNION ALL SELECT '20100919'
UNION ALL SELECT '20100920'
UNION ALL SELECT '20100922'
UNION ALL SELECT '20100923'
UNION ALL SELECT '20100925'
UNION ALL SELECT '20100928'
UNION ALL SELECT '20101002'
UNION ALL SELECT '20101004'
UNION ALL SELECT '20101007'
UNION ALL SELECT '20101009'
UNION ALL SELECT '20101010'
UNION ALL SELECT '20101013'
UNION ALL SELECT '20101016'
UNION ALL SELECT '20101018'
UNION ALL SELECT '20101019'
UNION ALL SELECT '20101020'
UNION ALL SELECT '20101022'
UNION ALL SELECT '20101023'
UNION ALL SELECT '20101025'
UNION ALL SELECT '20101028'
UNION ALL SELECT '20101030'
UNION ALL SELECT '20101102'
UNION ALL SELECT '20101107'
UNION ALL SELECT '20101108'
UNION ALL SELECT '20101109'
UNION ALL SELECT '20101111'
UNION ALL SELECT '20101112'
UNION ALL SELECT '20101114'
UNION ALL SELECT '20101117'
UNION ALL SELECT '20101119'
UNION ALL SELECT '20101124'
UNION ALL SELECT '20101126'
UNION ALL SELECT '20101127'
UNION ALL SELECT '20101129'
UNION ALL SELECT '20101201'
UNION ALL SELECT '20101203'
UNION ALL SELECT '20101204'
UNION ALL SELECT '20101206'
UNION ALL SELECT '20101209'
UNION ALL SELECT '20101210'
UNION ALL SELECT '20101213'
UNION ALL SELECT '20101214'
UNION ALL SELECT '20101215'
UNION ALL SELECT '20101216'
UNION ALL SELECT '20101220'
UNION ALL SELECT '20101222'
UNION ALL SELECT '20101227'
UNION ALL SELECT '20101228'
UNION ALL SELECT '20101229'
UNION ALL SELECT '20101230'
UNION ALL SELECT '20110102'
UNION ALL SELECT '20110103'
UNION ALL SELECT '20110104'
UNION ALL SELECT '20110106'
UNION ALL SELECT '20110107'
UNION ALL SELECT '20110108'
UNION ALL SELECT '20110109'
UNION ALL SELECT '20110110'
UNION ALL SELECT '20110111'
UNION ALL SELECT '20110114'
UNION ALL SELECT '20110116'
UNION ALL SELECT '20110118'
UNION ALL SELECT '20110119'
UNION ALL SELECT '20110120'
UNION ALL SELECT '20110122'
UNION ALL SELECT '20110123'
UNION ALL SELECT '20110125'
UNION ALL SELECT '20110126'
UNION ALL SELECT '20110128'
UNION ALL SELECT '20110130'
UNION ALL SELECT '20110203'
UNION ALL SELECT '20110205'
UNION ALL SELECT '20110206'
UNION ALL SELECT '20110208'
UNION ALL SELECT '20110210'
UNION ALL SELECT '20110212'
UNION ALL SELECT '20110213'
UNION ALL SELECT '20110215'
UNION ALL SELECT '20110218'
UNION ALL SELECT '20110221'
UNION ALL SELECT '20110224'
UNION ALL SELECT '20110226'
UNION ALL SELECT '20110301'
UNION ALL SELECT '20110302'
UNION ALL SELECT '20110304'
UNION ALL SELECT '20110307'
UNION ALL SELECT '20110309'
UNION ALL SELECT '20110311'
UNION ALL SELECT '20110314'
UNION ALL SELECT '20110316'
UNION ALL SELECT '20110317'
UNION ALL SELECT '20110320'
UNION ALL SELECT '20110321'
UNION ALL SELECT '20110323'
UNION ALL SELECT '20110326'
UNION ALL SELECT '20110328'
UNION ALL SELECT '20110329'
UNION ALL SELECT '20110331'
UNION ALL SELECT '20110403'
UNION ALL SELECT '20110405'
UNION ALL SELECT '20110406'
UNION ALL SELECT '20110408'
UNION ALL SELECT '20110410'
UNION ALL SELECT '20110415'
UNION ALL SELECT '20110416'
UNION ALL SELECT '20110417'
UNION ALL SELECT '20110418'
UNION ALL SELECT '20110421'
UNION ALL SELECT '20110422'
UNION ALL SELECT '20110423'
UNION ALL SELECT '20110426'
UNION ALL SELECT '20110429'
UNION ALL SELECT '20110501'
UNION ALL SELECT '20110503'
UNION ALL SELECT '20110504'
UNION ALL SELECT '20110506'
UNION ALL SELECT '20110508'
UNION ALL SELECT '20110509'
UNION ALL SELECT '20110511'
UNION ALL SELECT '20110512'
UNION ALL SELECT '20110514'
UNION ALL SELECT '20110517'
UNION ALL SELECT '20110518'
UNION ALL SELECT '20110519'
UNION ALL SELECT '20110520'
UNION ALL SELECT '20110522'
UNION ALL SELECT '20110526'
UNION ALL SELECT '20110531'
UNION ALL SELECT '20110603'
UNION ALL SELECT '20110604'
UNION ALL SELECT '20110605'
UNION ALL SELECT '20110606'
UNION ALL SELECT '20110608'
UNION ALL SELECT '20110611'
UNION ALL SELECT '20110613'
UNION ALL SELECT '20110614'
UNION ALL SELECT '20110616'
UNION ALL SELECT '20110622'
UNION ALL SELECT '20110624'
UNION ALL SELECT '20110627'
UNION ALL SELECT '20110703'
UNION ALL SELECT '20110704'
UNION ALL SELECT '20110711'
UNION ALL SELECT '20110712'
UNION ALL SELECT '20110713'
UNION ALL SELECT '20110714'
UNION ALL SELECT '20110719'
UNION ALL SELECT '20110720'
UNION ALL SELECT '20110725'
UNION ALL SELECT '20110726'
UNION ALL SELECT '20110802'
UNION ALL SELECT '20110804'
UNION ALL SELECT '20110811'
UNION ALL SELECT '20090611'
UNION ALL SELECT '20091124'
UNION ALL SELECT '20100201'
UNION ALL SELECT '20100202'
UNION ALL SELECT '20100204'
UNION ALL SELECT '20100220'
UNION ALL SELECT '20100305'
UNION ALL SELECT '20100323'
UNION ALL SELECT '20100414'
UNION ALL SELECT '20100417'
UNION ALL SELECT '20100508'
UNION ALL SELECT '20100512'
UNION ALL SELECT '20100527'
UNION ALL SELECT '20100616'
UNION ALL SELECT '20100702'
UNION ALL SELECT '20100705'
UNION ALL SELECT '20100707'
UNION ALL SELECT '20100708'
UNION ALL SELECT '20100710'
UNION ALL SELECT '20100711'
UNION ALL SELECT '20100712'
UNION ALL SELECT '20100717'
UNION ALL SELECT '20100719'
UNION ALL SELECT '20100722'
UNION ALL SELECT '20100723'
UNION ALL SELECT '20100724'
UNION ALL SELECT '20100725'
UNION ALL SELECT '20100730'
UNION ALL SELECT '20100805'
UNION ALL SELECT '20100806'
UNION ALL SELECT '20100808'
UNION ALL SELECT '20100812'
UNION ALL SELECT '20100814'
UNION ALL SELECT '20100815'
UNION ALL SELECT '20100816'
UNION ALL SELECT '20100818'
UNION ALL SELECT '20100821'
UNION ALL SELECT '20100824'
UNION ALL SELECT '20100826'
UNION ALL SELECT '20100829'
UNION ALL SELECT '20100903'
UNION ALL SELECT '20100906'
UNION ALL SELECT '20100912'
UNION ALL SELECT '20100914'
UNION ALL SELECT '20100915'
UNION ALL SELECT '20100917'
UNION ALL SELECT '20100918'
UNION ALL SELECT '20100921'
UNION ALL SELECT '20100924'
UNION ALL SELECT '20100926'
UNION ALL SELECT '20100927'
UNION ALL SELECT '20100929'
UNION ALL SELECT '20100930'
UNION ALL SELECT '20101001'
UNION ALL SELECT '20101003'
UNION ALL SELECT '20101005'
UNION ALL SELECT '20101006'
UNION ALL SELECT '20101008'
UNION ALL SELECT '20101011'
UNION ALL SELECT '20101012'
UNION ALL SELECT '20101014'
UNION ALL SELECT '20101015'
UNION ALL SELECT '20101017'
UNION ALL SELECT '20101021'
UNION ALL SELECT '20101024'
UNION ALL SELECT '20101026'
UNION ALL SELECT '20101027'
UNION ALL SELECT '20101029'
UNION ALL SELECT '20101031'
UNION ALL SELECT '20101101'
UNION ALL SELECT '20101103'
UNION ALL SELECT '20101104'
UNION ALL SELECT '20101105'
UNION ALL SELECT '20101106'
UNION ALL SELECT '20101110'
UNION ALL SELECT '20101113'
UNION ALL SELECT '20101115'
UNION ALL SELECT '20101116'
UNION ALL SELECT '20101118'
UNION ALL SELECT '20101120'
UNION ALL SELECT '20101122'
UNION ALL SELECT '20101123'
UNION ALL SELECT '20101125'
UNION ALL SELECT '20101128'
UNION ALL SELECT '20101130'
UNION ALL SELECT '20101202'
UNION ALL SELECT '20101205'
UNION ALL SELECT '20101207'
UNION ALL SELECT '20101208'
UNION ALL SELECT '20101212'
UNION ALL SELECT '20101217'
UNION ALL SELECT '20101218'
UNION ALL SELECT '20101219'
UNION ALL SELECT '20101221'
UNION ALL SELECT '20101223'
UNION ALL SELECT '20101224'
UNION ALL SELECT '20101226'
UNION ALL SELECT '20101231'
UNION ALL SELECT '20110101'
UNION ALL SELECT '20110105'
UNION ALL SELECT '20110112'
UNION ALL SELECT '20110113'
UNION ALL SELECT '20110115'
UNION ALL SELECT '20110117'
UNION ALL SELECT '20110121'
UNION ALL SELECT '20110124'
UNION ALL SELECT '20110127'
UNION ALL SELECT '20110129'
UNION ALL SELECT '20110131'
UNION ALL SELECT '20110201'
UNION ALL SELECT '20110202'
UNION ALL SELECT '20110204'
UNION ALL SELECT '20110207'
UNION ALL SELECT '20110209'
UNION ALL SELECT '20110211'
UNION ALL SELECT '20110214'
UNION ALL SELECT '20110216'
UNION ALL SELECT '20110217'
UNION ALL SELECT '20110219'
UNION ALL SELECT '20110220'
UNION ALL SELECT '20110222'
UNION ALL SELECT '20110223'
UNION ALL SELECT '20110225'
UNION ALL SELECT '20110228'
UNION ALL SELECT '20110303'
UNION ALL SELECT '20110305'
UNION ALL SELECT '20110306'
UNION ALL SELECT '20110308'
UNION ALL SELECT '20110310'
UNION ALL SELECT '20110312'
UNION ALL SELECT '20110313'
UNION ALL SELECT '20110315'
UNION ALL SELECT '20110318'
UNION ALL SELECT '20110322'
UNION ALL SELECT '20110324'
UNION ALL SELECT '20110325'
UNION ALL SELECT '20110327'
UNION ALL SELECT '20110330'
UNION ALL SELECT '20110401'
UNION ALL SELECT '20110404'
UNION ALL SELECT '20110407'
UNION ALL SELECT '20110409'
UNION ALL SELECT '20110411'
UNION ALL SELECT '20110412'
UNION ALL SELECT '20110413'
UNION ALL SELECT '20110414'
UNION ALL SELECT '20110419'
UNION ALL SELECT '20110420'
UNION ALL SELECT '20110425'
UNION ALL SELECT '20110427'
UNION ALL SELECT '20110428'
UNION ALL SELECT '20110430'
UNION ALL SELECT '20110502'
UNION ALL SELECT '20110505'
UNION ALL SELECT '20110507'
UNION ALL SELECT '20110510'
UNION ALL SELECT '20110513'
UNION ALL SELECT '20110515'
UNION ALL SELECT '20110516'
UNION ALL SELECT '20110521'
UNION ALL SELECT '20110523'
UNION ALL SELECT '20110524'
UNION ALL SELECT '20110525'
UNION ALL SELECT '20110527'
UNION ALL SELECT '20110528'
UNION ALL SELECT '20110530'
UNION ALL SELECT '20110601'
UNION ALL SELECT '20110602'
UNION ALL SELECT '20110607'
UNION ALL SELECT '20110609'
UNION ALL SELECT '20110610'
UNION ALL SELECT '20110615'
UNION ALL SELECT '20110617'
UNION ALL SELECT '20110618'
UNION ALL SELECT '20110620'
UNION ALL SELECT '20110621'
UNION ALL SELECT '20110623'
UNION ALL SELECT '20110626'
UNION ALL SELECT '20110628'
UNION ALL SELECT '20110629'
UNION ALL SELECT '20110630'
UNION ALL SELECT '20110701'
UNION ALL SELECT '20110706'
UNION ALL SELECT '20110707'
UNION ALL SELECT '20110708'
UNION ALL SELECT '20110715'
UNION ALL SELECT '20110717'
UNION ALL SELECT '20110721'
UNION ALL SELECT '20110722'
UNION ALL SELECT '20110727'
UNION ALL SELECT '20110729'
UNION ALL SELECT '20110801'
UNION ALL SELECT '20110810'

SELECT 
    CAST(RD.CompletionDate AS datetime) AS casts_fine
FROm
    @REAL_DATES RD

我很欣赏关于 SSIS 或其他方法的评论，但在游戏的这一点上，我们已经与 TSQL 转换方法结合了。如果有人能指出我遗漏了什么，我会以你的名字命名我的第一个孩子，假设你不介意把你的名字改成詹姆斯。

sql-server sql-server-2008

1 个回答

  1. Best Answer

    当你这样做时会发生什么？

    DECLARE @REAL_DATES TABLE
(
    CompletionDate VARCHAR(46)
);

INSERT INTO
    @REAL_DATES
    SELECT CompletionDate
    FROM dbo.Entity;

SELECT 
    CAST(RD.CompletionDate AS datetime) AS casts_fine
    FROM @REAL_DATES RD;

    我在 twitter 上得到的是优化器可以在行被消除之前尝试转换，因此您不能只考虑连接返回的 CompletionDate 值。

    My first suggestion would be to use the right data type. Why are you using VARCHAR(46) to store a date? This is why you have bad data in the table and why you have to explicitly convert when you want rich data that is not a string (and should never have been a string in the first place IMHO).

    My next suggestion would be to correct ALL data in that column, and put measures in place so that it won't become invalid again. For example, a check constraint that validates ISDATE(columnname) = 1.

    Failing those two, next on my list would be to return the data to the client and let it convert to datetime or for display or what have you. No matter where you filter out the rows that are causing the problem, the optimizer could push that evaluation around so that the convert is attempted before the bad rows are weeded out.

    And finally, you could dump the result of the query into a temp table / table variable, and perform the convert as a second step when querying that intermediate object (since you should be confident that the dates here are valid - in fact you can check first and raise an error if your join happened to return some rows with invalid dates).

    Bottom line: (a) you can't make any assumptions about where in the stack a conversion attempt will be made and (b) these workarounds and hacks would not be necessary if you used the right data type.

    • 8

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